The present invention relates to the regulation of a path length, i.e. the distance through which an object is displaced.
More particularly, the invention relates to a method of regulating a path length in dependence upon a variable control value.
The invention also relates to an arrangement for carrying the aforementioned method into effect.
A regulating method and arrangement of the general type here under discussion are disclosed in "Programminformation" (Hartmann & Braun, April 1977, Page 49, FIG. 6) which describes an electro-pneumatic position regulator designated IZIS. This regulator converts a control value, which is furnished as a variable electrical input signal, into a proportional path length or a proportional valve cross-section opening, respectively. The regulator essentially consists of a path-length furnishing unit, a differential amplifier, a current/pressure converter with a subsequent pressure amplifier and a pressure-responsive setting device which controls the opening of the valve cross-section. The differential amplifier is supplied with an input current proportional voltage as well as with a voltage which is derived from the path-length furnishing unit and which corresponds to the momentary valve position. The output signal of the current-to-pressure converter which is arranged subsequent to the differential amplifier, is converted into a pressure signal suitable for controlling the setting device, by the pressure amplifier.
A problem with this prior art construction is that the stability of the regulating circuit is determined by the dynamic behavior of the regulating stage. This makes it necessary in each instance to carry out an individual adaptation of the regulator to the regulating circuit which, in turn, means that the use of the arrangement with other regulating stages is often impossible, at least not without significant adjustment work.